another, other

I think about things.

私はことを考えます

I think about things today.

私は今日、ことを考えます

I think about things during the lesson today.

私は今日、授業中にことを考えます

I think about things during the lesson today because I am tired.

私は今日、授業中に疲れていてことを考えます

I think about other things during the lesson today because I am tired.

私は今日、授業中に疲れていてほかのことを考えます